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- Filesort has an optmization where it reads only columns that are needed before the sorting is done. - When ref(_or_null) is picked by the join optimizer, it may remove parts of WHERE clause that are guaranteed to be true. - However, if we use quick select, we must put all of the range columns into the read set. Not doing so will may cause us to fail to detect the end of the range.
13 lines
462 B
Text
13 lines
462 B
Text
drop table if exists t0,t1,t2,t3;
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#
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# MDEV-6434: Wrong result (extra rows) with ORDER BY, multiple-column index, InnoDB
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#
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CREATE TABLE t1 (a INT, b INT, c INT, d TEXT, KEY idx(a,b,c)) ENGINE=InnoDB;
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INSERT INTO t1 (a,c) VALUES
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(8, 9),(8, 10),(13, 15),(16, 17),(16, 18),(16, 19),(20, 21),
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(20, 22),(20, 24),(20, 25),(20, 26),(20, 27),(20, 28);
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SELECT * FROM t1 WHERE a = 8 AND (b = 1 OR b IS NULL) ORDER BY c;
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a b c d
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8 NULL 9 NULL
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8 NULL 10 NULL
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DROP TABLE t1;
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